1. Field of the Invention
The present invention relates to image forming apparatuses. More specifically, the present invention relates to an image forming apparatus such as a duplicating machine, facsimile apparatus and printer.
2. Description of the Related Art
Conventionally, an ink-jet type image forming apparatus is known. The ink-jet type image forming apparatus discharges an ink droplet from a nozzle of a liquid discharge head that is an ink discharge unit, and forms an image on a recording medium. One of this kind of ink-jet type image forming apparatuses forms an image by using a line head including nozzles arranged along a width direction across the full width of the recording medium. The ink-jet type image forming apparatus has a risk that as ink solvent evaporates from the nozzle, ink viscosity of the nozzle increases, clogging occurs, a normal ink discharge is prevented, and thus, an image failure occurs. Because of this, it is necessary to discharge the ink with increased viscosity from the nozzle by performing a blank discharge at regular intervals.
Japanese Laid-Open Patent Application Publication No. 2005-225207 and Japanese Laid-Open Patent Application Publication No. 2006-159556 disclose the following ink-jet type image forming apparatus. That is, the image forming apparatus includes a conveyor belt to convey a recording medium, including a plurality of blank discharge holes through which ink passes for a blank discharge, and performs a blank discharge toward the blank discharge holes from nozzles in a line head. The ink discharged from the line head by the blank discharge passes through the blank discharge holes of the conveyor belt. The image forming apparatus collects the ink in a blank discharge receiver provided facing the line head through the conveyor belt.
The conveyor belt is configured to rotate by being supported by a plurality of supporting rollers including a driving roller and a driven roller. Such a configuration of conveyor belt sometimes moves in a belt width direction, according to a belt state, physical environment in the device, installation condition and so on. If the conveyor belt moves in the belt width direction, positions of the blank discharge holes set at the conveyor belt become out of alignment in the belt width direction. As a result, some of the nozzles set to perform the blank discharge toward a certain blank discharge hole do not face the blank discharge hole, and the ink of the blank discharge adheres to the conveyor belt. If the ink adheres to the conveyor belt, a surface of the recording medium in contact with the conveyor belt becomes tainted by the ink adhered to the conveyor belt. Moreover, while fixing a paper jam, an operator sometimes touches the conveyor belt, which may soil the operator's clothes.